The present invention relates to a titanium/aluminum alloy suitable as material for members which are required to be resistant to heat at high temperatures (500 to 700.degree. C.) and medium temperatures, high in proof stress, and long in fatigue life such as compressor blades, spacers, etc. of gas turbines.
Conventionally, titanium/aluminum base alloys are known as brittle material although they have a proof stress of about 35 Kgf/mm.sup.2.
The above proof stress value remains until the alloys are heated to about 800.degree. C. and although the alloys exhibit a breaking extension of about 15% or over at high temperatures, when they are broken, cleavage planes are observed in many places on the broken surface, which is characteristic of unstable breakage.
A titanium/aluminum alloy made up of 50 to 63 wt. % of titanium, 5 to 50 wt. % of aluminum, 0.02 to 0.1 wt. % of boron, and other materials is suggested in Japanese Patent Application Laid-Open No. 61017/1990. Further, Japanese Patent Application No. 80661/1991 suggests a titanium/aluminum alloy made up of 50 to 65 wt. % of titanium, 35 to 50 wt. % of aluminum, 0.02 to 0.1 wt. % of boron. and other material wherein long .alpha..sup.2 -.gamma. layers are arranged in one direction.